The disclosure of Japanese Patent Applications No. 2001-130447 filed on Apr. 26, 2001 and No. 2002-59525 filed on Mar. 5, 2002, including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to a route navigation system, a client terminal, a server, a route navigation method, and a route identicalness determination method for performing route navigation for a user of the client terminal from a place of departure to a destination, through communication between the server at an information base and the client terminal.
2. Description of Related Art
Among the conventional route navigation systems that have been proposed, there is a navigation system in which a route navigation apparatus (client terminal) such as a navigation apparatus mounted in a vehicle carries out transmission and reception of information (data) to/from an information base (server), and thereby supplements data in the route navigation apparatus in order to properly perform route navigation from a place of departure P to a destination G. However, such a route navigation system involves a problem in that the amount of information (data) to be transmitted from the information base to the route navigation apparatus becomes large and communication cost is accordingly increased.
In view of such a problem, Japanese Laid-Open Patent No. 2000-18955 discloses a system in which the information base only transmits information concerning a route that a user has not traveled in the past to a route navigation apparatus, but does not transmit information concerning a route that the user has previously traveled to the route navigation apparatus to thereby decrease the amount of the information to be transmitted.
However, the above-described system has a problem in that the information base, even in the case where substantially the same information concerning the route is stored in the route navigation apparatus, transmits the information of the entire route to the route navigation apparatus if the entire route has never been traveled by the user, thus resulting in a problem in that the amount of the data to be transmitted is not sufficiently decreased.
One of the objects of the invention is achieved by a route navigation system, a client terminal, a server, a route navigation method, and a route identicalness determination method which decrease the amount of data to be transmitted from an information base to a route navigation apparatus (client terminal) through an effective use of data stored in the route navigation apparatus.
In a general description of the invention to be given below, a route navigation system provided with a server and a client terminal will be described as a typical example, and the description of the route navigation system will substitute for descriptions of the server and the client terminal, both of which are components of this route navigation system, a route navigation method which is an operating method of the route navigation system, and the route identicalness determination method according to the invention.
A route navigation system according to one aspect of the invention, which performs route navigation for a user of the client terminal from a place of departure to a destination, is constituted from:
a server including a server database, which determines a server route which is a route from the place of departure to the destination along with guiding points, using information in the server database; and
a client terminal, including a client terminal database, which, communicating with the server, determines a client route which is a route from the place of departure to the destination, along with guiding points, using information in the client terminal database.
The server or the client terminal determines whether or not a route between adjoining guiding points of the server route and a route between adjoining guiding points of the client route are identical by at least comparing positions of the guiding points of the server route and the client route. Then, the client terminal, based on a result of the above determination, selectively uses information concerning the client route in the client terminal database and information concerning the server route in the server database in performing the route navigation. At this point, it should be noted that physically separate servers may be used for determining the server route and for making the above-described comparative determination, which are respectively constructed from physically separate computers which are connected to and communicate with one another.
The server determines the server route which is a route from the place of departure to the destination using the information (data) in the server database which is its own database, and the server route includes the guiding points. On the other hand, the client terminal determines the client route, which is a route from the place of departure to the destination, using the information (data) in the client terminal database which is its own database, and the client route also includes the guiding points.
Next, in the above-described comparative determination by the server or the client terminal, the positions of the guiding points of the server route and the client route are compared to each other, and, based on a result thereof, it is determined whether or not the route between the adjoining guiding points of the server route and the route between the adjoining guiding points of the client route are identical. Then, according to the result thereof, the information in the server and the client terminal are selectively used in performing the route navigation.
In this way, at least when the guiding points of the server route and the client routes are identical, and therefore it is determined that the route between the adjoining guiding points of the server route and the route between the adjoining guiding points of the client route are substantially the same, the information concerning the client route in the client terminal database is effectively used and thereby it becomes possible to decrease the amount of the data (information) concerning the server route to be transmitted to the client terminal from the server.
Further, a route navigation system according to one embodiment of the invention is a route navigation system which performs route navigation for a user of the client terminal from a place of departure to a destination, including:
a server including a server database, which determines a server route which is a route from the place of departure to the destination using the information in the server database; and
a client terminal including a client terminal database which, communicating with the server, performs the route navigation based on the information in the client terminal database and the information in the server database, in which
the client terminal obtains guiding point information (information concerning guiding points) of the determined server route and, taking one of adjoining guiding points of the server route specified in the obtained information as the outgoing-side guiding point and the other one of those adjoining guiding points as the incoming-side guiding point, determines a client route therebetween using the information in the client terminal database, and
the client terminal determines whether or not the server route between the adjoining guiding points and the determined client route are identical, and if they are identical, performs the route navigation of the route between the adjoining guiding points using the information in the client terminal database, and if they are not identical, obtains the information concerning one or more sections or entire sections of the server route between the adjoining guiding points from the server and performs the route navigation based thereon.
As described above, the server determines the server route which is a route from the place of departure to the destination, using the information in the server database. This route includes the guiding points. On the other hand, the client terminal obtains the guiding point information of the server route from the server and, using the information in the client terminal database, determines the client route between the adjoining guiding points specified in the guiding point information obtained from the server, taking one of those adjoining guiding points as the outgoing-side guiding point and the other one of those as the incoming-side guiding point.
The client terminal thereafter determines whether or not the server route between the adjoining guiding points and the determined client route are identical. if they are identical, the client terminal performs the route navigation of the route between the adjoining guiding points using the information in the client terminal database. If they are not identical, the client terminal obtains the information concerning one or more sections or entire sections of the server route between the adjoining guiding points from the server and performs the route navigation based thereon. The information concerning one or more sections or entire sections of the server route between the adjoining guiding points may be minimal information which is necessary for performing the route navigation, but also may be map data for surrounding areas of the route between the adjoining guiding points, including the above minimal information.
Accordingly, the information in the client terminal database is at least used for performing the route navigation of the route in the section where the server route between the adjoining guiding points and the determined client route are identical. Thus, it is not necessary to transmit the information concerning the server route in those sections to the client terminal from the server and therefore the amount of the information to be transmitted from the server to the client terminal is decreased. Further, since the client terminal determines the client route to each adjoining guiding point of the server route, compared to the case where the client route is determined for the entire route from the place of departure to the destination at once using the information in the client terminal database, the compared portions of the server route and the client route are more likely to be identical. Also in this viewpoint, the amount of the information to be transmitted to the client terminal from the server is decreased in the above-described construction.
According to a further aspect of the invention, there is provided a route navigation system that performs a communication between a server having a server-side database and a client terminal having a client terminal-side database, and performs a route navigation from a place of departure to a destination for a user of the client terminal while selectively using information from the server-side database and information from the client terminal-side database in the route navigation system, the client terminal transmits at least information for specifying the place of departure and the destination to the server, obtains a point that can be a first guiding point that is a guiding point adjacent to the place of departure as a first guiding candidate point by searching information stored in the client terminal-side database. The server obtains a server route that is a route from the place of departure to the destination using information stored in the server-side database based on the information for specifying the place of departure and the destination which information is transmitted from the client terminal, and transmits information regarding a guiding point included in the server route obtained to the client terminal. The client terminal further receives information regarding the guiding point of the server route obtained, determines whether the first guiding candidate point includes a point identical to the first guiding point specified by the received information regarding the guiding point of the server route, performs the route navigation regarding a segment from the place of departure to the first guiding point using the information stored in the client terminal-side database if there is a first guiding candidate point identical to the first guiding point, and performs the route navigation by acquiring information regarding a segment from the place of departure to the first guiding point from the server if there is not a first guiding candidate point identical to the first guiding point.
In this route navigation system, the client terminal transmits at least information for specifying a place of departure and a destination to the server, and obtains a point that can be a first guiding point that is a guiding point adjacent to the place of departure as a first guiding candidate point by searching information stored in the client terminal-side database. The place of departure is known to the client terminal. Therefore, the client terminal is able to obtain first guiding candidate points through the use of only information stored in the client-side database. In other words, the client terminal is able to start an operation of obtaining first guiding candidate points at a stage preceding acquisition of information from the server.
On the other hand, the server obtains a server route that is a route from the place of departure to the destination through the use of information stored in the server-side database based on the information from the client terminal for specifying the place of departure and the destination. To obtain such a route, in general, a process termed xe2x80x9croute calculationxe2x80x9d which is more complicated and requires more time than a simple data search is needed. Therefore, during the course of the server obtaining a server route, the client terminal starts search of first guiding candidate points, and therefore can finish the entire search or can finish at least a portion of the search.
Furthermore, after the server obtains a server route, the client terminal receives information regarding guiding points of the server route, and determines whether the first guiding candidate points include a point identical to the first guiding point (first guiding point on the server route) specified by the acquired information regarding the guiding points of the server route.
If there is a first guiding candidate point identical to the first guiding point of the server route, the client terminal performs the route navigation regarding the segment from the place of departure to the first guiding point (i.e., the identical first guiding candidate point) through the use of information stored in the client terminal-side database. If there is not a first guiding candidate point identical to the first guiding point of the server route, the client terminal performs the route navigation by acquiring information regarding a segment from the place of departure to the first guiding point from the server.
Thus, since the client terminal starts search regarding first guiding candidate points during the process of the server obtaining a server route, the client terminal is able to finish the entire search of first guiding candidate points or finish at least a portion of the search by the time of receiving information regarding guiding points on the server route. Therefore, within a short time before the time point of reception, the client terminal is able to determine which one of the client terminal-side database and the server-side database stores information to be used for the segment from the place of departure to the first guiding point, within a short time before the time of receiving the information. Therefore, the client is able to quickly acquire at least information regarding the first guiding point within a short time period following a request for route navigation (i.e., following a departure of the vehicle). Hence, route navigation appropriate to a user can be performed. Furthermore, if a first guiding candidate point identical to the first guiding point on the server route exists and information stored in the client terminal-side database can be used, information regarding the segment related to the first guiding point is not transmitted. Therefore, only information for specifying the guiding points on the server route is transmitted, so that the amount of information transmitted can be reduced.
According to a further aspect of the invention, there is provided a route navigation system that performs a communication between a server having a server-side database and a client terminal having a client terminal-side database, and performs a route navigation from a place of departure to a destination for a user of the client terminal while selectively using information from the server-side database and information from the client terminal-side database. In the route navigation system, the client terminal transmits at least information for specifying the place of departure and the destination to the serve. The server obtains a server route that is a route from the place of departure to the destination using information stored in the server-side database based on the information for specifying the place of departure and the destination which information is transmitted from the client terminal, and transmits guiding point information regarding a guiding point included in the server route obtained to the client terminal. The client terminal further acquires the guiding point information of the server route from the server, and for obtaining a point that can be an adjacent guiding point that is a guiding point adjacent to an arbitrary guiding point of guiding points specified by the acquired guiding point information, at a destination side of the arbitrary guiding point, as an adjacent guiding candidate point by searching information stored in a client terminal-side database, determines whether the adjacent guiding candidate point includes a point identical to an adjacent guiding point of the server route which is a guiding point adjacent to the destination side of the arbitrary guiding point and which is specified by the acquired guiding point information, performs the route navigation regarding a segment from the arbitrary guiding point to the adjacent guiding point of the server route using the information stored in the client terminal-side database if there is an adjacent guiding candidate point identical to the adjacent guiding point of the server route, and performs the route navigation by acquiring information regarding a segment from the arbitrary guiding point to the adjacent guiding point of the server route from the server if there is not an adjacent guiding candidate point identical to the adjacent guiding point of the server route.
In this route navigation system, the client terminal transmits at least information for specifying a place of departure and a destination to the server. The server obtains a server route that is a route from the place of departure to the destination through the use of information stored in the server-side database based on the information from the client terminal for specifying the place of departure and the destination. To obtain such a route, in general, a process termed xe2x80x9croute calculationxe2x80x9d which is more complicated and requires more time than a simple data search is needed. Then, the server transmits guiding point information regarding guiding points included in the obtained server route to the client terminal.
On the other hand, the client terminal receives the information regarding guiding points of the obtained server route, and obtains a point that can be an adjacent guiding point that is a guiding point adjacent to an arbitrary guiding point of guiding points specified by the received guiding point information, at a destination side of the arbitrary guiding point, as an adjacent guiding candidate point by searching information stored in the client terminal-side database. Since this process is a data searching process, it is often the case that the process ends in a shorter time than a calculation of a route between adjacent guiding points.
Then, the client terminal determines whether the adjacent guiding candidate points include a point identical to an adjacent guiding point of the server route which is specified by the received guiding point information. In accordance with the result of the determination, the client terminal performs the route navigation regarding the segment from the arbitrary guiding point to the adjacent guiding point of the server route either by using information stored in the client terminal-side database, or by acquiring information regarding the segment from the server and using the acquired information.
Therefore, the client terminal is able to determine route information to be used, and is able to acquire the information, through simple data search without performing a route calculation that has a great calculation load and needs a relatively long time. Therefore, it becomes possible to quickly perform route navigation at precise timing.